Commit 7cb70266 authored Sep 09, 2021 by David Hildenbrand Committed by Christian Borntraeger Oct 25, 2021

s390/mm: optimize set_guest_storage_key()



We already optimize get_guest_storage_key() to assume that if we don't have
a PTE table and don't have a huge page mapped that the storage key is 0.

Similarly, optimize set_guest_storage_key() to simply do nothing in case
the key to set is 0.

Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20210909162248.14969-9-david@redhat.com


Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

parent 8318c404

arch/s390/mm/pgtable.c

+12 −2

Original line number	Diff line number	Diff line
		@@ -792,13 +792,23 @@ int set_guest_storage_key(struct mm_struct *mm, unsigned long addr,
		pmd_t *pmdp;
		pte_t *ptep;

		if (pmd_lookup(mm, addr, &pmdp))
		/*
		* If we don't have a PTE table and if there is no huge page mapped,
		* we can ignore attempts to set the key to 0, because it already is 0.
		*/
		switch (pmd_lookup(mm, addr, &pmdp)) {
		case -ENOENT:
		return key ? -EFAULT : 0;
		case 0:
		break;
		default:
		return -EFAULT;
		}

		ptl = pmd_lock(mm, pmdp);
		if (!pmd_present(*pmdp)) {
		spin_unlock(ptl);
		return -EFAULT;
		return key ? -EFAULT : 0;
		}

		if (pmd_large(*pmdp)) {